Many types of spray guns for the dispensing of coating materials (hereinafter sometimes paint) are known. There are, for example, the devices illustrated and described in U.S. Pat. Nos. 7,380,680; 7,354,074; 7,353,964; 7,350,418; 7,344,040; 7,165,732; 7,143,960; 7,090,148; 7,086,549; 6,953,155; 6,945,429; 6,796,514; 6,749,132; 6,712,292; 6,698,670; 6,663,018; 6,595,441; 6,543,708; 6,536,687; 6,588,681; 6,189,809; 5,836,517; 5,803,367; 5,582,350; 5,485,860; 5,366,158; 5,267,693; 5,209,365; 5,174,317; 5,119,992; 5,054,687; 4,978,072; 4,941,614; 4,793,369; 4,760,962; 4,746,063; and references cited in these; and JP H07-194997-A; JP H09-70557-A; JP H09-187682-A; and JP H11-319641-A. The disclosures of these references are hereby incorporated herein by reference. This listing is not intended to be a representation that a complete search of all relevant art has been made, or that no more pertinent art than that listed exists, or that the listed art is material to patentability. Nor should any such representation be inferred.
Many of these types of devices are used in facilities that repair the finishes of, for example, automotive vehicles. Automobile body shops are examples of such facilities. It is typical in such facilities that smaller amounts of coating materials are used than in, for example, an automobile finishing line in a manufacturing facility. As a result, typically, the spray guns that are used in such repair facilities are equipped with paint cups into which an amount of paint necessary to effect a repair is placed, and from which the paint flows or is drawn as paint is sprayed during the repair process. If more paint is needed, the repair is interrupted and additional paint is added as many times as are necessary to complete the repair. The guns typically one of two types: pressure or suction feed guns, in which cases the paint cup is mounted under the gun and a feed tube or siphon projects into the volume of paint in the cup to withdraw paint as the paint is being dispensed; and, gravity feed guns, in which case the cup is mounted on top of the gun and the paint flows from the cup into the gun under the influence of gravity when the gun trigger is actuated to be delivered to the gun's spray nozzle and dispensed.
In many cases, such guns are provided with, or coupled to, high-magnitude electrostatic potential sources which supply high-magnitude electrostatic potentials to electrodes with which the guns are equipped. The high-magnitude potential aids in atomization and dispensing of the coating material in accordance with know principles and results in more efficient deposition of the sprayed coating material on the object, or target, repair of which is being effected.
Finally, in many cases, the guns dispense water-base coating materials. Such materials generally are electrically non-insulative. Consequently, protection against leakage of charging voltage from the electrodes of such guns through the water-base coating materials being dispensed by such guns to ground is an issue which must be dealt with in gun design and construction.